1. Technical Field
The present invention relates to a data administration method, and more particularly to data operating administration in encrypting and distributing digital content.
2. Description of Related Art
In software such as a computer program and in electronic publications, electronic data is stored on magneto optical disks (MOs), digital video disks (DVDs), floppy disks (FDs), mini-disks (MDs) or other recording media and then sold. Such electronic data is in general easily copied, and unfair copies are made frequently. Therefore, there is a risk that copyrights on the software vendor's or publisher's end will be infringed, damaging profits dramatically.
Likewise unfair copies are frequently made of electronic data, including still image data, moving image data, audio data or music data, that is distributed through the internet, CATV or other networks, spoiling copyright holders' profits.
Thus in order to protect so-called digital content such as electronic data stored on recording media and electronic data distributed through various networks, the digital content is encrypted by using an encryption key, and the encrypted real data is distributed.
For example, a conceivable case is that of a user gaining access from a personal computer to content on a distributor end, and downloading the digital content onto and using it from the user's hard disk. First, the user accesses a host computer and gets a plug-in module for downloading. Thereafter, an identification number for the hard disk drive being used, an identification number for the CPU being used, and user-specific identification information are sent to the host computer end.
On the content distributor end, real data in which digital content is encrypted with a content key, and consent information in which the content key is encrypted with the user-specific identification information, is transmitted to the user end.
On the user end, the encrypted real data sent in, and the consent information are recorded on the hard disk in the as-is-encrypted state. When the digital content is to be used, utilizing the hard disk drive identification number and other user-specific identification information, the consent information is decrypted to obtain the content key. The encrypted digital content is decrypted using the content key and then used.
In this case, in granting to users individually the right to use digital content, the encryption key for encrypting the digital content can be made common, and encrypting decryption keys using user-specific identification information that is different for each user enables use rights to be granted individually.
Distributing data by the above-described method necessitates that the data distributor send encrypted digital content, and consent information that becomes a decryption key for the encrypted digital content, separately.
Also, on the user end encrypted digital content and its consent information sent in have to be stored onto the recording medium separately.
Consequently, in instances in which consent information is destroyed en route while being sent from the data distributor end to the user end, or else due to some accident on the user end, consent information on the recording medium is destroyed or lost, the digital content becomes unusable. This makes it necessary once again to go through the procedure for obtaining the consent information.
Furthermore, where image data is taken from library manuscripts and art museum collections by photographing or scanning and made available to users, complete encryption of the image data makes it difficult on the user end to specify desired image data before the exchange for consent information is carried out. Accordingly, it would be desirable to manage the data so that a part of the image can be recognized on the user end, and moreover so that the data cannot misappropriated.
Not only in cases in which still- or moving-image image data is encrypted and distributed, but also in which audio data and music data is, being able to recognize visually or auditorily what sort of digital content is contained in data would be convenient for the user.